please help with question below, working required?

Question

The voltage drop (v) volts across an inductor of L Henries at time (t)seconds is given by:
v=150e^RT/L
where R = 100ohms and L = 8 x 10^-3 H
a) Find the value of the voltage when t = 80 x 10^-6 s
b) Plot the graph of v against t for t = 0 to t = 400 x 10^-6s.
c) Find the time for the voltage to reach 70V.

Answer 1

Both a and b are straightforward, just use the values given to compute the answers.

a) V=150 e^ -(R/L)t (notice a negative sign in the exponent)
Just plug the numbers

(I got your message. I could not respond back. Blocking on your end. )

Sorry I made a mistake it should be 70 not 50 so
c) 70=150 e (-R/L)t

70/150= e^(-R/L)t
1/3=e ^/L)t
ln(.466667)=ln(e^(-R/L)t)
ln(.46667)= (-R/L)t
then
t=-L/R ln(.46667)
t=-[(8 x 10^-3 h)/( 100 ohms )]ln(.466667)=
t=6.1e-5
t=61 uSec